7 or 8 tendon breakages in less than 2 years with Chinook mast base - Chinook tendons (mainly), also tried Streamlined and Severne tendons.

Paul (ex 2ndWind) thought I might have had a bad batch of tendons and sourced me a couple of Chinook tendons from different batches but no tendon has lasted more than about 3 months. He also had a good look at the mast base but couldn’t see anything obviously wrong with it. Thanks Paul and 2ndWind

Lao has had a close look too, we think it might be a machining tolerance issue that can’t be seen, no other explanation.
I bought the Chinook mast base because I wanted the strongest available. I think I might buy another and just accept that there is something wrong with the one I’ve got.

Unless somebody has an answer?


Yes I sail often (and use only the Chinook mast base), but others who sail just as frequently aren’t having the breakages.

BTW, using Formuline rope and a mast base pad is a lifesaver (keeping the rope pretty tight, but allowing proper movement).
Yesterday’s break was a mile out in the ocean. I heard the click when the tendon broke, the board trim felt slightly odd but I couldn’t see what was wrong. Sailed back to the beach at full speed (unaware of the breakage) with no damage to the board.

This latest Chinook tendon had started to deform after only a couple of sessions and was only a couple of months old.

Thanks for any suggestions. JJ

JJ,
I was only thinking about this the other day. I too only use the Chinook uni (both the one above and the quick release deck plate/pin one) and always ensure that the spare tendons I purchase are authentic chinook. I went a longtime with no breakages then had a spate of them in fairly quick succession. I kept my spares in the tray of a plastic toolbox and thought that maybe off gassing or chemical reaction of the tray and tendon combined affected the tendon's mechanical / chemical properties. the toolbox never sees the light of day and stored in a fairly controlled (temp) environment so I can eliminate heat factors. Out of interest as I am a bit of a bower bird I kept all my old replaced tendons that were in one piece in the same toolbox and went to reuse when I had ran out of new spares. A light bend of the uni I quickly discovered that these old tendons had perished and easily broke apart. So I now keep my spares in paper bags - whether this has any effect I wouldn't have a clue and it'd be great to hear from a mechanical chemist on possible theories for accelerated perishing / polymer degradation.

Have you checked the edges of the machined parts as any small nick on top edges could be making small nicks in tendon when bent right over - I had to file and sand smooth the burrs on one that had clashed / rubbed together when I broke a tendon.

One other factor to consider is that doing a lot of ocean sailing would stress the tendon more so than estuary or flat water sailing.

Also totally agree with you on the formuline as it has saved me every single time I've broken one. In fact I've sailed on before oblivious to the fact the tendon had broken.

previous threads here too JJ -
www.seabreeze.com.au/forums/Windsurfing/General/Check-my-Tendon/
www.seabreeze.com.au/forums/Windsurfing/General/Tendon-Mast-Base-Euro-Style-Pin-Trouble/?page=1
www.seabreeze.com.au/forums/Windsurfing/General/Best-boge/

I also only use the Chinook mast bases, and like sausage, the one above and the quick release deck plate/pin ones.

Last season (summer of 2014/2015) I snapped six or seven tendons, both chinook brand and severne. Previous years I would be lucky to snap one per season.

All my sailing is open ocean waves, but no different to previous seasons and I'd had the chinook bases for a couple of seasons. The only difference I could see to my sailing was possibly more aggressive jumping/twisting of the rig, but I'm not doing the type of acrobatics you see Jaeger etc doing so that seems unlikely.

End of last season I resigned myself to the fact that I would just need a bunch of tendons every season so I bought half a dozen chinook tendons online from an American shop and put these in my bases and kept the rest as spares.

I haven't snapped a single tendon this season, the tendons look fine and the spares are sitting there also looking fine.

Snags
Interesting you've had similar problems. I don't think it's a Chinook problem as I've had failures equally quickly with other brands.
I had a look at your wounded tendons - mine look the same often after only a few sessions, then always break within a couple of months.

I'm eager to see if someone can say definitively that the polymer can degrade without correct storage.

I've checked the mast base a few times for burrs but I'll certainly have another look.

Thanks for the links - seems Vando goes through a tendon every 3 months too.

Somebody commented that the if the rope is too tight it could constrain the normal bending of the tendon and perhaps weaken it.
Mine seems to have plenty of movement, perhaps an issue though?
Clutching at straws for now.


Thanks Spurgeo
Seems like you're none the wiser for the sudden rash of breakages?

^^

Thanks AUS4

Anyone out there thrashed the mechanical mast base and can recommend it?

Select to expand quote

AUS4 said..
http://chinooksailing.com/index.php/windsurf/bases/euro-pin/1-bolt-mechanical-mast-base-euro-pin-ex.html

Chinook make a mechanical base , you may want to look at that one.

Thanks Rick - very interested to know just how stiff these would feel in comparison to the dampening effect of the tendon.
this shows the mechanism a little better too chinooksailing.com/index.php/windsurf/bases/euro-pin/2-bolt-quick-release-mechanical-upper-euro-pin-ex.html

use a mechanical base for a number of reasons
mostly because they go to 90 degrees and then one can put large sails on wide boards without flipping the board
the side benefit is that there are NO breakable parts
as I am an average Joe windsurfer , I have seen NO downside to using them !!!
use them in the winter on my ice and snow sailboards as well !!



these ones need to be sharpened, put mast base and tested

I don't feel any wiser Azymuth

I don't think I can make any conclusions on my experiences. Would ideally need to test hundreds over many seasons with set/standard conditions.

I pay more attention to maintenance of that area now, make sure the safety rope is always in good condition, physically bend and inspect the tendons regularly and if they look dodgy I'll replace them.

Windsurfing can be a bit rough on gear and body, if something is going to give, I'd rather break a few mast base tendons each season than masts, boards or the tendons in my ankles etc

Strange, I also use the same brand but with the cup, not the euro pin, for years, always in the surf (mostly 4.2 to 5.7), and have never had a tendon fail in the middle. The few failures I've had have always been where the mounting screws go thru the tendons, either on the top or the bottom. It's easy to spot before the failure because the uni won't stand straight up after the sail is disconnected, it will be crooked because there is a tear starting inside the top or bottom collar, at the mounting pin.
Maybe either mine have looser collars, or your collars are too tight around the tendon, I'm getting 3 years with each tendon easy, some even longer.

Hi I used to use the skinny tendons (streamline) brand was good till it was showing stress lines ect,
Changed the tendon with in 3 sessions tendon broke,changed it again ,tendon broke ,I would have to put it down to bad batch, heat, bad chemical mix. Most of the boys use tendons and don't have any issues, go figure.
I use the hourglass bogie joint with much more success, they all break but these seem to be a bit more reliable, my 2 cents

Never yet broken a Chinook tendon and i use them for a couple of seasons
In summer the gear lives in a plastic box in the back of the car so gets plenty hot.

I am thinking batch issue as I have not replaced a tendon for almost 3yrs now - and yours seem to be newer ones breaking....

I sail lots and use Chinook tendons mines 1.5 years old I'll replace it at the end of the season. I keep my spare in an air tight container inside a way from heat and light. I think its a bad batch, maybe they outsourced to a cheaper country, maybe Chinook needs to do their own quality control testing like putting sample ones in a machine that bends them day and night until they break. Why not email Chinook?

I've never broken a Chinook tendon. They are the only ones I have ever used. I have two of the stainless steel cast bases that share the action each season and I put in new tendons every season and the bases stay in the van year-round. I sail about 3000km per year in open water.

You guys must be windsurfing super hard and long, maybe you need more downhaul?
I use a mix of various bases and replace the tendons every 1~2 years, no breakage so far.

Select to expand quote

shinobi said..
You guys must be windsurfing super hard and long, maybe you need more downhaul?
I use a mix of various bases and replace the tendons every 1~2 years, no breakage so far.

very true! but no need for various bases .. but a very good idea to change once in awhile .. hoping these manufacturers stamp an expiry date

This year I have replaced 2 chinook tendons and had a North Tendon break while I was about 2km off shore, had to self rescue and made a mess of the deck of my board due to design of North Shox extension.

I have not broken a UJ for many years, so 3 failures in a year is shocking

I always check the condition of the tendon before sailing - the 2 Chinook tendons I replaced due to visible cracks, but they did not fail on the water. The North Tendon safety rope inside also failed.... not much of a safety feature if it is not up to the job

I don't think i'll try the tendon style base any time soon, only busted one uni in the last 10 years (corrosion had got in around the nut and it pulled out of the rubber) only buy the cheaper makes/brands and retire them after 5ish years.

Bad batch!!! that was what i was told after going through the same problem,,to many bad batches for my liking, will never use tendons again. Stick with the fat boags . No excuse for bad batches!!! its a critical component that can leave you in dire situations in a breakage…Bad Batch,Blks

When I used to work in a shop I sold a few of these when they first came out, I also got one, mine had never broken a tendon and I sailed it for a few years, I still have it and think it is on the original tendon.

But I sold one to a friend from the same batch and he snapped a few within weeks of getting it, we found that the edge of the stainless cup the tendon sits in was a lot sharper than the others in the batch, he just rounded the edge off and cleaned it up and it sorted the problem.

Also check to see if the extension rotates properly on the pin as this could be twisting the tendon and weakening it.

I simply refuse to use a Tendon.
You cannot see if it's about to shear through the holes without pulling it to bits so you might as well just replace it while you're at it.
I have seen heaps break but very few Boge style.
I used Hydrodynamix Unis for years & don't think I ever had one break and I only got the seconds that were not good enough to sell
I think I changed them out around 4 or 5 years.
When they were no longer manufactured I went to Boge & have never had one break (yet) and I can see if it is about to break quite easily.
I have heard all the arguments about how much better & stiffer the Tendons are but don't give a rats, I like security & an un-damaged board.
If the swim saver rope is not real short the broken Tendon will punch nice holes in the deck sailing home

North have a hollow Tendon with a St St wire through the centre, pretty clever but don't know how long they last or how hard it is to inspect the tendon & wire for wear.

Yeah but with a Boge you can't see if the nylon safety strap is too worn at the end. I'd rather have a tendon breakage and know the visible and strong downhaul ropes will hold it all together, than busta Boge and find out the webbing strap is worn and it goes ping! also

A volcano pad stops the deck damage unless it is long sail home.
And again, never broken a tendon in 20yrs.

Tomato tomayyyyto